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O: Fachverband Oberflächenphysik

O 64: Oxides and Interfaces: Adsorption II

O 64.1: Vortrag

Mittwoch, 9. März 2016, 15:00–15:15, H6

Ab initio wave-function-based methods for highly accurate description of adsorption — •Denis Usvyat — Institut für Physikalische und Theoretische Chemie, Universtät Regensburg, 93040 Regensburg, Deutschland

The wave-function-based hierarchy of electronic structure models represents a convergent theory in a sense that it systematically approaches the exact solution within the Born-Oppenheimer approximation. Conventionally these models are computationally quite intensive and for decades were hardly applicable to extended systems. We show that by employing local approximations for the electronic correlations it becomes possible to overcome the issues of the computational complexity and treat periodic systems at a very high ab initio level. Furthermore, a combined periodic/finite-cluster approach allows one even to reach accuracy that surpasses the experimental one.

Physisorption on surfaces is one of the fields, where this technique is especially powerful. Indeed, the small energy scale and shallowness of the potential energy surfaces set high demands on the accuracy. On several examples we demonstrate that progressive elimination of various sources of errors, which is possible within the hierarchical wave-function-based treatment, leads to a sub-kJ/mol (or meV) accuracy in the interaction energies for small molecules adsorbed on non-conducting surfaces. Due to the unbiased character of this approach, it can be used to resolve experimental controversies, which are common in studies of physisorption.